Technical Field
The present disclosure relates generally to the field of defensive common infrared counter measure systems. More particularly, the present disclosure relates to defensive infrared systems having an electro-optical system disposed within protective dome on an aircraft. Specifically, the present disclosure relates to a hyper hemispherical dome on an infrared countermeasure system having a look angle greater than 180 degrees to allow two cooperating countermeasure systems mounted to an aircraft to fully observe incoming threats rather than prior art systems that require at least three counter measure systems.
Background Information
Infrared Countermeasures (IRCM) are infrared guidance systems configured to track strong sources of infrared radiation, namely heat, from aircraft engines. This helps missiles to hone in on their targets. IRCM systems have a modulated source of infrared radiation with a higher intensity than that of the target. When a missile seeker observes this modulated radiation, it interferes with or obscures the modulated signal from the aircraft and renders the missile incapable of maintaining a lock on the target.
Directional IRCM, or DIRCM, has a countermeasure laser to directly target an incoming IR threat. This makes a more powerful and effective defense than previous, non-directional infrared countermeasures, as the threat is directly addressed rather than the system essentially painting an area with IR disruption, which results in a weaker signal in any given direction.
Generally, airborne infrared (IR) countermeasure systems are required to defeat missile threats over a full spherical coverage range of 360 degrees. To defeat advanced threats high powered laser systems are required that are directed on the threat by advanced gimbals. Threats can come from any direction and thus gimbals are required to quickly and accurately move to the threat location. For these gimbals to work they need to be protected in sealed housings and must look through advanced windows that operate with maximum optical transmission and quality in the infrared spectrum. These windows will see harsh environments which limits window materials and configurations. Existing infrared window technologies are flat windows or domes that limit coverage to less than 180 degrees requiring more than two gimbals to provide 360 degrees coverage. Bonded hyper-hemispherical domes made of multiple pieces can be fabricated but bonded seams interfere with countermeasure performance.
As IR seeking technology has improved and diversified, standard IRCM systems have become less effective at defeating heat-seeking missiles. Measures such as flares have begun to give way to lasers, which, when fitted on a directional pivoting mount, allow for more effective, concentrated and energy-efficient directional targeting of IR radiation at incoming missile seekers.
In an effort to continue advancement of DIRCM technology, the United States Department of Defense (DoD) instituted a program called the Common Infrared Countermeasures program (CIRCM). CIRCM intended for defense contractors to develop a lightweight, low-cost and modular laser-based infrared protection system for U.S. helicopters and light fixed-wing aircraft. The CIRCM technology will provide defense against shoulder-fired, heat-seeking missiles, or MANPADS. The CIRCM program replaces older legacy systems such as the Advanced Threat Infrared Countermeasures (ATIRCM).
The CIRCM system meets Tri-Service “common” Army, Navy, and Air Force requirements. The DoD's strategy is to competitively develop a lightweight and cost-effective jammer subsystem for installation on all DoD rotary-wing and slow moving fixed-wing aircraft.
One government contractor, recently published their device for the CIRCM program. This contractor's device uses a compact ECLIPSE pointer/tracker, a COTS processor and Quantum Cascade Laser (QCL). The ECLIPSE pointer/tracker is available for public inspection at http://www.northropgrumman.com/Capabilities/CIRCM/Documents/CIRCMdatasheet.pdf.
A review of this contractor's CIRCM ECLIPSE pointer/tracker discloses a modular unit having a hemispherical dome housing electro-optical (EO) elements therein intended to provide defensive measures meeting the needs of the CIRCM. Particularly, the hemispherical dome appears to be a less than 180 degree dome (exact half a sphere, also referred to as a hemisphere) extending upward from a modular housing. A less than 180 degree infrared (IR) dome is easily fabricated.